Method, portable data carrier, and system for releasing a transaction using an acceleration sensor to sense mechanical oscillations

ABSTRACT

A method, a portable data storage medium, an approval apparatus and a system for approving a transaction using acceleration sensors integrated in a portable data storage medium.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method, a portable data carrier, a releaseapparatus and a system for releasing a transaction using accelerationsensors.

2. Related Art

According to this application an acceleration sensor will be understoodto be a sensor that ascertains the acceleration of a body, for exampleby determining the inertial force acting on a test mass. There are knownaccording to the prior art semiconductor-based acceleration sensors androtation sensors. Such an acceleration sensor measures linearself-motions and accelerations and subsequently, on the basis of themeasurement result, triggers switching operations in dependence on theself-motion in space. A rotation sensor ascertains the rotationalself-motion around an axis. Merely by way of example, the single-axisrotation sensor LY530AL and the three-axis rotation sensor LIS344ALHfrom the company ST Microelectronics are stated as electronic componentshere.

The possibility of integrating a motion sensor into a portable datacarrier, in particular in the form of a chip card, is known from thelaid-open application DE 102 48 389. The motion sensor is used hereexclusively for capturing lettering.

A problem of portable data carriers consists in the fact that they canbe read out via a contactless interface from a distance, for examplethrough a pocket, unnoticed by the owner. Especially critical in thisconnection is the possibility of a relay attack, because here aconnection is set up via a radio link to an “authentic” reading device.Such an attack is described for example in Chapter 8 of the book“Handbuch für Chipkarten” by Rankl, Effing or in Chapter 8 of the book“RFID-Handbuch” by Finkenzeller. The relay attack is also referred to inthe literature as a ghost-and-leech attack.

According to the prior art it is proposed to avoid this problem by forexample equipping portable data carriers with a push-button. Theinstallation of a push-button in a chip card or security token is veryelaborate, however, and causes high production costs. Being a mechanicalcomponent, a push-button is furthermore always subject to wear and canalso cause difficulties due to contact problems.

From the publication “RFIDs and Secret Handshakes: Defending AgainstGhost-and-Leech Attacks and Unauthorized Reads with Context-AwareCommunications”, published at the 15th ACM Conference of Computer andCommunications Security 2008, pages 479 to 490, there is known thepossibility of capturing characteristic gestures using an accelerationsensor in order to release the access to a data carrier.

This use of gestures seems impracticable from today's point of view.With passive portable data carriers which are equipped without abattery, the range for making gestures is of a similar size to the rangein which communication can be effected at all between the portable datacarrier and an end device, in particular a reading device, because poweris available to the data carrier for performing its measurements andcalculations only in this range. Upon the use of reading devicesaccording to ISO/IEC 14443 with a typical range of for example 10 cm,the latitude for motion for making a gesture within the reading range ofa card is thus greatly limited. In addition, there is a possiblepsychological barrier to making complex gestures with the portable datacarrier on an end device, for example a POS terminal or a transportticket machine in public.

From the patent print EP 1 745 420 B1 it is known, on the other hand, todesign the card body of a chip card with an inhomogeneous material. Thecharacteristic self-oscillations arising from the material of the cardupon excitation of the chip card are evaluated and the chip card therebyidentified. This method appears very cost-intensive, because each cardbody must be individual.

The object of the present invention is therefore to show a method, asystem, a portable data carrier and a release apparatus with which therelease of a transaction between a portable data carrier and an enddevice is effected more cost-efficiently, more securely more easily.

A transaction will be understood according to this application to be alogical sequence of operations. A transaction is for example a paymentoperation between a portable data carrier and an end device via acontactless interface. A transaction is alternatively also the readoutof security-critical information, for example PIN numbers, personal dataor general secrets, such as TAN numbers, passwords and so forth.

SUMMARY OF THE DISCLOSURE

According to the invention, the object is achieved by a method forreleasing a transaction between a portable data carrier and an enddevice by the portable data carrier first being brought into anelectromagnetic field. The EM field is generated here by the end device.The EM field serves as a power supply and for activating the portabledata carrier. At first, no transactions are released between theportable data carrier and the end device that include security-relevantinformation or data. Subsequently, the portable data carrier is excitedby mechanical oscillation. These mechanical oscillations aresubsequently captured in the portable data carrier by means ofacceleration sensor. Subsequently, the output signal of the accelerationsensor is evaluated or analyzed with regard to characteristic propertiesof the mechanical oscillation. As soon as a characteristic property ofthe oscillation has been recognized through the evaluation of the outputsignal, there is effected the releasing of the transaction by theportable data carrier.

A portable data carrier according to this application is, in principle,not of any predetermined form or configuration. In particular, aportable data carrier is understood to be a chip card, smart card, or ingeneral a security token for example with an identification function.Alternative configurations, for example as a mass memory card, forexample μSD card, are likewise conceivable. Further, it is understoodaccording to this application to be an electronic passport or differentkind of identification medium which contains security-criticalinformation that should not generally be read out of the data carrier.In the broader sense, the portable data carrier is a mobile phone withwhich transactions can be carried out with an end device, for examplevia a near-field communication. The mobile phone as a portable datacarrier here has a near-field communication interface.

An end device is understood to be any type of communication device withwhich the portable data carrier can communicate in particularcontactlessly. A communication is effected by way of example with areading device, also designated a terminal, standardized according toISO/IEC 14443. The end device is for example a POS terminal or atransport ticket machine with a near-range communication interface.

An oscillation fundamentally describes the periodic course of a changeof state of a physical quantity. A kind of mechanical oscillation isunderstood to be for example a vibration, an abrupt placement or therubbing/bending of the data carrier.

Through the method of the invention, a portable data carrier isprevented in simple fashion from carrying out a transaction with an enddevice without the transaction having been previously released. In thismanner there are prevented for example relay attacks or transactions notdesired by the user of the portable data carrier.

In an advantageous embodiment, the portable data carrier is set intoself-oscillation by the mechanical excitation. Subsequently, thisself-oscillation of the data carrier is captured in the form ofacceleration by the acceleration sensor and evaluated. The advantage inthis embodiment is to be seen in that an acceleration of the datacarrier is readily evaluable with minimum excitation.

Advantageously, the characteristic property is the time duration, thefrequency and/or the amplitude of the mechanical oscillation. Therefore,a transaction is only released when a target value of the characteristicproperty of the oscillation is exceeded, otherwise the transaction isnot released.

In an advantageous embodiment, the excitation of the data carrier iseffected with mechanical oscillation by the end device. For thispurpose, the data carrier is placed on the end device. Parts of thesurface of the end device are set oscillating in particular by amechanism. Alternative methods for exciting the surface to oscillate arelikewise conceivable. The portable data carrier is excited by thismechanical oscillation. The accelerometer in the data carrier capturesthese mechanical oscillations by the data carrier itself beingaccelerated in at least one direction. As mechanical oscillations thereare advantageously provided vibrations with deflections in themillimeter or sub-millimeter range. The user of the portable datacarrier is actively involved in the transaction releasing method throughplacement on the end device.

A simple and thereby advantageous embodiment is given when the enddevice is equipped with an oscillatable partial surface. This partialsurface becomes oscillating by means of linear or circular motions, forexample of a mechanism in the end device, and excites the placed-onportable data carrier. Preferably, the end-device antenna which isprovided for emitting the electromagnetic field is incorporated in orunder the oscillatable partial surface of the end device. Thus, thealready small range for communication between end device and datacarrier is not additionally reduced by the method of the invention.

In a preferred embodiment, the linear or circular oscillations of theend device are fluctuating in frequency. Alternatively or additionally,several linear or circular mechanical oscillations are superimposed. Thefluctuation of the frequencies and/or the oscillation superimpositionare evaluated as the characteristic property in the portable datacarrier. It is thus possible to realize different types of release forcommunication between data carrier and end device. A correspondingcoding is likewise possible.

By the emission of further linear or circular oscillations by the enddevice during the transaction it is possible to convey different statusmessages or status information of the transaction, for example the endor the failure of a transaction.

In an alternative embodiment of the invention, the exciting of the datacarrier with mechanical oscillation is effected such that the datacarrier is abruptly deposited on the end device. The abrupt placement isevaluated as the characteristic property of the mechanical oscillations.In particular, the self-acceleration of the portable data carrier beforethe abrupt placement and/or an angle acquisition after the abruptplacement are evaluated as the characteristic property of the mechanicaloscillations here.

In a further alternative embodiment, the portable data carrier isexcited mechanically by being moved or rubbed on an outer surface of theend device. The oscillations arising from the friction are captured asaccelerations in the portable data carrier and evaluated.

The bringing of the portable data carrier into an EM field for supplyingpower can be omitted insofar as the data carrier has its own powersupply, for example in the form of an accumulator, a battery and/or aphotovoltaic cell. In this embodiment the EM field is unnecessary forsupplying power; the release of a transaction will nevertheless proceedby the method of the invention in order to prevent for example thereadout of security-relevant or security-critical information of theabove-described type.

Likewise provided according to the invention is a portable data carrierfor data transfer with an end device, whereby the data carrier has arelease apparatus and the release apparatus comprises an accelerationsensor, wherein mechanical oscillations of the data carrier areascertainable by the acceleration sensor, and an evaluation unit,wherein the evaluation unit is provided for evaluating the accelerationsensor output signals and ascertains the mechanical oscillations. A datatransfer between portable data carrier and end device is releasable assoon as the evaluation unit generates a release signal by reason of amechanical-oscillation characteristic required for the release.

Further, there is contained in the scope of the invention a module forreleasing a transaction with an end device. The module comprises anacceleration sensor for capturing a mechanical oscillation, anevaluation unit for evaluating the captured mechanical oscillation,whereby the mechanical oscillation is evaluated with regard tocharacteristic properties, a comparing unit for comparing thecharacteristic properties of the mechanical oscillation of theevaluation unit with a target value of the characteristic properties,whereby the comparing unit releases the transaction when the targetvalue of the characteristic property is exceeded, and the comparing unitdoes not release the transaction when the target value of thecharacteristic property is undershot.

The target value could be stored in a data storage in the data carrierand be retrieved during the evaluation of the characteristic property ofthe oscillation.

Finally, there is provided according to the invention a system forreleasing a transaction. The system comprises a portable data carrier,including an above-described module for releasing a transaction with anend device, and the end device itself, whereby the portable data carrieris excitable with a mechanical oscillation, and the comparing unit ofthe module releases the transaction upon exceeding of a target value ofa characteristic property of the mechanical oscillation.

An advantage of the method of the invention is the use of the card inthe way that the user is accustomed to. For this purpose, there areemployed semiconductor components which can be integrated simply into ahardware module, for example into a chip module of a chip card as theportable data carrier.

DESCRIPTION OF THE DRAWINGS

There are shown:

FIG. 1 a block diagram of a portable data carrier according to theinvention with a release apparatus for releasing a transaction in a planview

FIG. 2 a block diagram of a portable data carrier according to theinvention according to FIG. 1 as a cross-sectional drawing

FIG. 3 a block diagram of a transaction releasing system according tothe invention

FIG. 4 a sketched representation of an oscillatable partial surface,according to the invention, of an end device with an oscillationgenerating apparatus

FIG. 5 a detailed block diagram of a release apparatus according to theinvention for incorporation into a portable data carrier according toFIG. 1 or 2

FIG. 6 an exemplary voltage-time curve of the acceleration sensor outputsignals in X, Y and Z directions upon exciting of the data carrier bymeans of mechanical oscillations generated by the end device

FIG. 7 an exemplary voltage-time curve of the acceleration sensor outputsignals in X, Y and Z directions upon exciting of the data carrier byabrupt placement of the data carrier

FIG. 8 exemplary acceleration sensor output signals in X, Y and Zdirections upon placement of the data carrier on a 30° inclined surface

FIG. 9 an exemplary amplitude-frequency curve of the acceleration sensoroutput signals in X, Y and Z directions by FFT analysis of the curveshown in FIG. 6

FIG. 10 a flowchart of a method according to the invention for releasinga transaction between a portable data carrier and an end device

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

In FIG. 1 there is represented a block diagram of a portable datacarrier 1 according to the invention with a release apparatus 7 forreleasing a transaction in a plan view. The portable data carrier 1 isrepresented here in the form of a chip card or smart card. Forcommunication with an end device (not represented here) there isincorporated into the body of the data carrier 1 an antenna 2 fornear-field communication or NFC. The antenna 2 is electrically coupledwith antenna terminals to an integrated circuit 3. By the EM field andthe antenna 2 the integrated circuit 3 is supplied with power andactivated. The integrated circuit 3 has the release apparatus 7.Further, the portable data carrier 3 has acceleration sensors 4, 5, 6incorporated therein. The acceleration sensor 4 captures accelerationsin the X direction, the sensor 5 accelerations in the Y direction, andthe acceleration sensor 6 in the Z direction. The output signals 4 a, 5a and 6 a of the acceleration sensors 4, 5, 6 are supplied to theintegrated circuit 3.

In FIG. 2 there is represented the portable data carrier 1 from FIG. 2as a cross section in a block diagram.

When the portable data carrier 1 according to FIG. 1 or 2 is broughtinto an electromagnetic field, or EM field for short, generated by anend device, the antenna 2 draws power from the generated EM field andmakes this power available to the integrated circuit 3. According to theinvention it is provided to evaluate the output signals 4 a, 5 a, 6 a ofthe acceleration sensors 4, 5, 6 with regard to a characteristicproperty upon the entry and sojourn of the data carrier 1 and to derivetherefrom the decision to release or not release a contactlesstransaction. The integrated circuit 3 thus gives no release of atransaction with the end device until the acceleration sensors 4, 5, 6capture accelerations in that form and supply them as output signals 4a, 5 a, 6 a to the integrated circuit 3, so that a characteristicproperty of mechanical oscillation has been ascertained.

As the characteristic property that for release of a transaction betweenend device and data carrier 1 there can be considered for example a timeduration T, an amplitude height of the output signals 4 a, 5 a 6 a, asequence of an intensity fluctuation, or a special frequency of thecaptured accelerations. These characteristic properties can also bearbitrarily combined for a required release.

In FIGS. 1 and 2, the acceleration sensors 4, 5, 6 are incorporated intothe body of the portable data carrier 3 separately from the circuit 3.Alternatively and preferably, the acceleration sensors 4, 5, 6 areincorporated in the integrated circuit 3. Alternatively, only oneacceleration sensor or at least one rotation sensor (not represented inthe figures) can be provided instead of the three acceleration sensors4, 5, 6.

The data carrier 1 is constituted such that it carries out asufficiently detectable acceleration in the interior of the data carrierbody upon excitation by means of mechanical oscillation.

In FIG. 3 there is represented a system, according to the invention, forreleasing a transaction between a portable data carrier 1 and an enddevice 8. The data carrier 1 corresponds here to the data carrier 1described in FIGS. 1 and 2. The end device 8, or terminal, is notlimited in its function, being for example a reading device. The enddevice 8 has an antenna 12. Thus, a near-field communication 9 takesplace contactlessly by means of the antennas 2 and 12. Additionally, theend device 8 has an oscillatable partial surface 10. With this partialsurface 10 mechanical oscillations 13 are performed. The mechanicaloscillation 13 a is excited here by the end device 8 itself. The antenna12 of the reading device is preferably housed in or under theoscillatable partial surface, e.g. in a coaxial arrangement.

The mechanical oscillations exciting the portable data carrier 1 aregenerated by the end device 8 in FIG. 3 and can be for example linear orcircular.

FIG. 4 shows an example for generating a circular oscillation of thepartial surface 10. For this purpose, the partial surface 10 issuspended concentrically on a flywheel 11. A rotational motion 13 a ofthe flywheel 11 leads to a circular motion of the partial surface 10. Inpractice the oscillations have an amplitude in the millimeter orsub-millimeter range. Oscillation frequencies can be in the range of afew hertz up to a few tens of hertz. Such mechanical oscillations arehumanly perceived as vibration, similar to the vibration alarm of amobile phone.

For carrying out a transaction, for example a payment transaction orreadout of security-critical information, it is provided that the datacarrier 1 of the invention is deposited on the surface 10 of an enddevice 8 according to the invention. For releasing the data exchange orcommunication with the data carrier 1 it is provided that a vibration isfirst generated at a certain time before the transaction. This vibrationis transferred to the data carrier 1 and captured by the accelerationsensors 4, 5. The type of vibration, the amplitude and the frequency ofthe vibration can be easily captured here via the sensor output signals4 a, 5 a, 6 a.

An example of the sensor measured values of a pulsed circular vibrationis represented in FIG. 6. The three measured curves represent here theoscillation axes X, Y, Z, in accordance with the signals 4 a, 5 a, 6 aof the acceleration sensors 4, 5, 6. According to the invention it isprovided that the data carrier 1 analyzes and evaluates the oscillationpatterns of the captured oscillations with regard to at least onecharacteristic property. If the measured values are within a tolerancerange of an expected range, it is provided that the intended transactionwith the data carrier 1 is released. Alternatively, it is also possibleto release the access to a selected storage area of the data carrier 1and/or the further communication between the end device 8 and the datacarrier 1. The tolerance range can also be a target value threshold ofone of the characteristic properties of the oscillation, which must beexceeded for release.

One possible option consists in the vibration signal also being outputto the user of the data carrier 1 for signaling operating states. Whenthe data carrier 1 is held with the hand on a corresponding end device8, the vibrations are easy to feel. This is advantageous insofar as a“beep signal” is easily missed in a noisy environment, while a “flashingsignal” cannot be recognized by blind people. Thus, the first vibrationwhich leads to release of a transaction, etc., can be followed by asecond vibration for signaling a successful transaction to the user. Akind of coding of the vibration can also signal to the user that atransaction was successful, for example an intensity fluctuation of thevibration (rrr - - - rrr) for a successful transaction, and longconstant-intensity vibration (rrrrrrrrrrrrrr) upon the occurrence of anerror. The evaluation, calculation and rating of the mechanicaloscillations is carried out for example by software on the integratedcircuit 3.

A further option consists in the data carrier 1 analyzing oscillationparameters determined by the end device 8, in particular the frequency.A further possibility also consists in superimposing several oscillationfrequencies. Such a superimposed oscillation can be very easilygenerated for example with an electromagnetic oscillator system.

Using an FFT it is easy to check the occurrence of the differentoscillation frequencies. In FIG. 9 this is represented by way of exampleby the calculated FFT signals 4 c, 5 c, 6 c. Through the performed FFTthe spectrum of the evaluated sensor output signals 4 b, 5 b, 6 b showsthe individual frequency components in the signals after an FFTanalysis.

A detailed block diagram of a circuit 3 incorporated in the portabledata carrier 1 as in the previous figures is represented in FIG. 5. Thesensors 4, 5, 6 are likewise arranged within the integrated circuit 3here. The output signals 4 a, 5 a, 6 a of the sensors 4, 5, 6 aresupplied to the evaluation unit 7 a. An evaluation of the signals can befor example the amplitude height, the time duration, etc. In principle,these evaluated signals can be supplied directly to the comparing unit 7c in order to be compared there optionally with target value stored in atarget value storage 7 d in the data carrier 1. Upon exceeding of thetarget value the release of the transaction is effected through arelease signal 7 e. Alternatively, as represented in FIG. 6, theevaluated signals are first supplied to a calculation unit 7 b. Thiscalculation unit 7 c calculates the signals 4 c, 5 c, 6 c. As thecalculation there is provided for example an FFT analysis or thecalculation of the static angle of the data carrier from the evaluatedsignals 4 b, 5 b, 6 b.

In a second embodiment of the invention it is provided that the datacarrier 1 is not excited by mechanical oscillations generated by the enddevice. For example, the data carrier 1 can be excited by the datacarrier 1 being placed abruptly on a surface, for example a surface inproximity of the antenna 12 of the end device 8, and remaining thereduring the transaction. The abrupt placing, striking or thudding of thedata carrier 1 leads to high acceleration values 21, as represented inFIG. 8. The self-acceleration 20 of the data carrier 1 before the abruptplacement is also well recognizable in FIG. 8. By means of thecalculation unit 7 b it is possible for example to evaluate which staticangle the data carrier 1 has at the moment. FIG. 8 shows the measuredvalues of a data carrier 1 in the rest position on a 30° inclinedsurface.

According to the invention it is therefore provided that the datacarrier 1, upon entry into the communication range of an end device 8,measures the acceleration and analyzes and evaluates the measuredvalues. After the abrupt placement of the data carrier 1 on the surfaceof the reading device there is ascertained the static position, forexample the angle, of the data carrier 1, which is normally resting flaton the surface of the end device 8. If the measured values are within atolerance range of an expected range, it is provided that the intendedtransaction with the data carrier 1, the access to a selected storagearea of the data carrier and/or the further communication between theend device 8 and the data carrier 1 is released.

One option consists in arranging the contact surface (antenna area) ofthe reading device at a defined angle, e.g. 30°, see FIG. 8. The datacarrier 1 can check after being placed on the surface of the end device8 whether this angle is adhered to within defined tolerance ranges.

An alternative excitation of the data carrier 1 is effected by a userrubbing the data carrier 1 to and fro on a surface of the end device 8.Thereby resulting mechanical oscillations or the self-acceleration ofthe data carrier 1 are captured by the acceleration sensors 4, 5, 6 andevaluated.

In FIG. 10 there is represented an exemplary flowchart for a method,according to the invention, for releasing a transaction between enddevice 8 and portable data carrier 1. By provision 14 of an EM field bythe end device 8 the portable data carrier 1 is electrically activated15. By mechanical excitation 16 by means of mechanical oscillation, forexample vibration, abrupt placement with resulting high accelerationvalues 20, 21, or rubbing together of the surfaces of data carrier 1 andend device 8, and subsequent capturing 17 of the acceleration in X, Y, Zdirections by means of the sensors 4, 5, 6, it is possible to ascertainthe accelerations by evaluation and/or calculation 18 of theacceleration sensor output signals 4 a, 5 a, 6 a. In step 19 there iseffected the comparison of the signal values with regard tocharacteristic properties, such as for example frequency, amplitude,time duration, static angle, frequency fluctuation, frequencysuperimposition, frequency components or the like. In method step 22there is finally effected the release of the transaction upon exceedingof a target value or upon adherence to a defined tolerance range. Targetvalues and tolerance range are preferably stored in a storage area ofthe data carrier 1.

The method of the invention is preferably implemented at least partly inthe form of computer software in the integrated circuit 3. Theintegrated circuit 3 then performs the corresponding method steps asimplemented program steps.

As a further, case of application of the invention there is provided thecarrying out of a transaction with an NFC-capable mobile phone as theportable data carrier. A user wishing for example to carry out a paymenttransaction now need not confirm it with the keyboard of his mobilephone, but rather the release of the transaction is effected accordingto the described subjects of the invention. By excitation of the mobilephone as the portable data carrier by means of mechanical oscillation,the release of the transaction is effected as soon as characteristicproperties of the oscillations have been captured and evaluated in themobile phone. This patent application synonymously employs the termsmobile phone, PDA, communication device, organizer, electronic calendarand the like.

The decisive advantage of both embodiments consists in that the expectedmotion patterns of the data carrier 1 cannot be provided unnoticedly byan attacker having no mechanical access to the card, such as for examplein a typical relay attack. The absolute position of the card cannot bechanged unnoticedly by an attacker either.

The invention claimed is:
 1. A method for releasing a transactionbetween a portable data carrier and an end device, the method comprisingthe steps: a) bringing the portable data carrier into an electromagneticfield generated by the end device and drawing power by the data carrierfrom the electromagnetic field for the power supply of the data carrier,b) exciting the portable data carrier by mechanical oscillationgenerated by the end device, wherein the end device generates linear,circular, or a combination of linear and circular mechanicaloscillations and mechanically excites the portable data carrier by thelinear, circular, or the combination of linear and circular mechanicaloscillations, c) capturing the mechanical oscillation in the portabledata carrier by means of an acceleration sensor, d) evaluating an outputsignal of the acceleration sensor with regard to characteristicproperties of the mechanical oscillation, and e) releasing thetransaction by the portable data carrier as soon as a characteristicproperty of the oscillation has been recognized through the evaluationof the output signal.
 2. The method according to claim 1, wherein theportable data carrier is set into self-oscillation by the mechanicalexcitation, and this self-oscillation is captured and evaluated.
 3. Themethod according to claim 1, wherein as the characteristic property thetime duration, the frequency or the amplitude of the mechanicaloscillation is evaluated.
 4. The method according to claim 1, whereinthe end device excites the portable data carrier via an oscillatablepartial surface of the end device.
 5. The method according to claim 4,wherein the linear or circular mechanical oscillations of the end devicefluctuate in frequency, and the frequency fluctuation is evaluated asthe characteristic property in the portable data carrier.
 6. The methodaccording to claim 4, wherein several linear or circular mechanicaloscillations of the end device are superimposed, and this oscillationsuperimposition is evaluated as the characteristic property in theportable data carrier.
 7. The method according to claim 4, whereinfurther linear or circular oscillations are emitted during thetransaction.
 8. The method according to claim 4, wherein an antenna ofthe end device emits the electromagnetic field and the electromagneticsignal is incorporated in or under the oscillatable partial surface ofthe end device.
 9. The method according to claim 4, wherein the enddevice vibrates.
 10. The method according to claim 1, wherein theportable data carrier is excited mechanically by placing the portabledata carrier abruptly on the end device, and the abrupt placement isevaluated as the characteristic property of the mechanical oscillations.11. The method according to claim 10, wherein: the self-accelerationand/or high acceleration values before the abrupt placement and/or anangle acquisition after the abrupt placement are evaluated as thecharacteristic property of the mechanical oscillations.
 12. The methodaccording to claim 1, wherein the portable data carrier is excitedmechanically by rubbing the portable data carrier on an outer surface ofthe end device.
 13. A portable data carrier for transferring data withan end device, wherein the data carrier includes a release apparatus,said release apparatus comprising: an acceleration sensor configured toascertain mechanical oscillations generated by the end device and togenerate acceleration sensor output signals, wherein the end devicegenerates linear, circular, or a combination of linear and circularmechanical oscillations and mechanically excites the portable datacarrier by the linear, circular, or the combination of linear andcircular mechanical oscillations, and an evaluation unit that evaluatesthe acceleration sensor output signals and ascertains the mechanicaloscillations, a data transfer between portable data carrier and enddevice being releasable upon the evaluation unit generating a releasesignal by reason of a mechanical-oscillation characteristic required forthe release.
 14. A module for releasing a transaction with an enddevice, comprising: an acceleration sensor for capturing a mechanicaloscillation generated by the end device, wherein the end devicegenerates linear, circular, or a combination of linear and circularmechanical oscillations and mechanically excites the portable datacarrier by the linear, circular, or the combination of linear andcircular mechanical oscillations, an evaluation unit for evaluating thecaptured mechanical oscillation, wherein the mechanical oscillation isevaluated with regard to characteristic properties, a comparing unit forcomparing the characteristic properties of the mechanical oscillation ofthe evaluation unit with a target value of the characteristicproperties, wherein the comparing unit releases the transaction when thetarget value of the characteristic property is exceeded, and thecomparing unit does not release the transaction when the target value ofthe characteristic property is undershot.
 15. A system for releasing atransaction comprising: a portable data carrier, including the modulerecited in claim 14, and an end device, wherein the portable datacarrier is excitable with the mechanical oscillation generated by theend device, and the comparing unit of the module for releasing releasesthe transaction upon exceeding of a target value of a characteristicproperty of the mechanical oscillation.